mirror of
https://github.com/dj0abr/SSB_HighSpeed_Modem.git
synced 2024-11-15 16:42:07 -05:00
84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
/*
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* High Speed modem to transfer data in a 2,7kHz SSB channel
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* =========================================================
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* Author: DJ0ABR
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*
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* (c) DJ0ABR
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* www.dj0abr.de
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include "qo100modem.h"
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// since we use a static crc register we need TWO separated registers
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// for RX and TX to get it thread safe, no.2 is for file ID generation
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uint16_t reg16[3] = {0xffff,0xffff}; // shift register
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uint16_t Crc16_bytecalc(int rxtx, uint8_t byt)
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{
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uint16_t polynom = 0x8408; // generator polynom
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for (int i = 0; i < 8; ++i)
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{
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if ((reg16[rxtx] & 1) != (byt & 1))
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reg16[rxtx] = (uint16_t)((reg16[rxtx] >> 1) ^ polynom);
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else
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reg16[rxtx] >>= 1;
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byt >>= 1;
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}
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return reg16[rxtx];
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}
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uint16_t Crc16_messagecalc(int rxtx, uint8_t *data,int len)
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{
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reg16[rxtx] = 0xffff;
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for (int i = 0; i < len; i++)
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reg16[rxtx] = Crc16_bytecalc(rxtx,data[i]);
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return reg16[rxtx];
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}
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// =================================================================
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uint32_t reg32[2] = {0xffffffff,0xffffffff}; // Shiftregister
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void crc32_bytecalc(int rxtx, unsigned char byte)
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{
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int i;
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uint32_t polynom = 0xEDB88320; // Generatorpolynom
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for (i=0; i<8; ++i)
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{
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if ((reg32[rxtx]&1) != (byte&1))
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reg32[rxtx] = (reg32[rxtx]>>1)^polynom;
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else
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reg32[rxtx] >>= 1;
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byte >>= 1;
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}
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}
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uint32_t crc32_messagecalc(int rxtx, unsigned char *data, int len)
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{
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int i;
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reg32[rxtx] = 0xffffffff;
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for(i=0; i<len; i++) {
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crc32_bytecalc(rxtx,data[i]);
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}
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return reg32[rxtx] ^ 0xffffffff;
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}
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